Adiabatic L-shell ionization of Hg and Tl by proton and He ion impact

Abstract

L-shell x-ray production cross sections by proton and 4 He ion impact on Hg and Tl (of great importance from the biological point of view, owing to their moderate toxicity properties) have been measured in the energy ranges 0.3 E p 2.6 MeV and 0.7 E4 He 1.8 MeV, respectively. L-subshell ionization cross sections have been extracted and arranged, together with the few existing data from other laboratories, in an analysis aimed at testing the performance of various theoretical approximations in the description of the ionization process. The disagreement observed at low values of the reduced velocity parameter ξ R L between the data and the predictions of the ECPSSR model is reduced significantly by using a united-atom approximation in the treatment of the binding correction, suggested by our group (ECPSSR-UA). The remaining discrepancies, mostly for the L 1 -subshell, are strongly reduced by replacing the screened hydrogen-like wavefunctions with the more realistic Dirac-Hartree-Slater ones. In the case of 4 He ions, especially for the L 2 -subshell, a more refined Coulomb deflection correction and/or more sophisticated coupled-channels calculations are also needed.